Many energetic materials of importance to Department of Defense (DoD) applications, such as bis-dinitropropyl acetal-formal (BDNPA/F), 2,2’,4,4’,6,6’-hexanitrostillbene (HNS), 2,2-dimethyl-2,2-dinitrobutane (DMDNB), 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), and 1,3,3-trinitroazetidine (TNAZ), share energetic structural elements consisting of nitro groups bound to carbon atoms. The production of such materials is generally accomplished with numerous powerful chemical oxidizers. Use of these reagents generates pernicious waste streams, and these chemical oxidizers are themselves environmentally costly to produce. The developent of environmentally benign production methods for these energetic materials would be beneficial to DoD.
The objective of this project was to develop a general technology for the synthesis of energetic materials using clean electrochemical oxidation methodology. This approach eliminates the use of strong chemical oxidizing agents and thus their byproducts and waste streams, providing a more environmentally sound manufacturing approach.
This project explored the application of electrochemical oxidation technology to manufacture energetic materials of DoD interest such as BDNPA/F, TNAZ, TATB, and HNS. The oxidation of trinitrotoluene (TNT), 1-t-butyl-3-hydroxymethyl-3-nitroazetidine (HMNAz), phloroglucinol, and nitroethane were carried out under electrochemical conditions to manufacture the target compounds. These oxidations were evaluated for their efficacy and ability to be scaled to industrially useful quantities. Cursory economic feasibility of the approach at a production scale was estimated, and recommendations were made for further pursuit.
Voltammetric investigations and electrochemical synthesis of the targeted chemistries were performed with several of these applications appearing to be promising. An electrochemical oxidation cell was used to perform bulk electrolysis experiments to isolate quantities of some of these materials for chemical identification. DMDNB, 2,2-dinitropropanol (DNPOH), the precursor to BDNPA/F, and 1-tert-butyl-3,3-dinitroazetidine (DNAZ), the precursor to TNAZ, were isolated and characterized. Application of this approach to manufacturing of these materials appears feasible, pending further development. Work to develop an electrochemical oxidation process continues under SERDP project WP-1460.
Electrochemical reactions are among the cleanest of chemical conversion alternatives in that only electricity, catalytic electrode surfaces, and a solvent are required. Organic materials are minimized, and solvents may be recycled and reused. The industrial production of energetic materials using electrochemical synthesis could dramatically reduce the environmental impact of their manufacture by removing the need for chemical oxidizers and avoiding also the costs incurred in the disposal of waste by-products (Project Completed - 2004)